The Korean names for the language are based on the names for Korea used in North and South Korea.

In North Korea and Yanbian in China, the language is most often called Chosŏnmal (조선말; with Hanja:朝鮮말), or more formally, Chosŏnŏ (조선어; 朝鮮語).

In South Korea, the language is most often called Hangungmal (한국말; 韓國말), or more formally, Hangugeo (한국어; 韓國語) or Gugeo (국어; 國語; literally "national language"). It is sometimes colloquially called Urimal ("our language"; 우리말 in one word in South Korea, 우리 말 with a space in North Korea).

On the other hand, Korean people in the former USSR, who refer to themselves as Koryo-saram (also Goryeoin [고려인; 高麗人; literally, "Goryeo person(s)"]) call the language Goryeomal (고려말; 高麗말).

The classification of the modern Korean language is uncertain, and due to the lack of any one generally-accepted theory, it is sometimes described conservatively as a language isolate.

Since the publication of the article of Ramstedt in 1926, many linguists support the hypothesis that Korean can be classified as an Altaic language, or as a relative of proto-Altaic. Korean is similar to Altaic languages in that they both have the absence of certain grammatical elements, including number, gender, articles, fusional morphology, voice, and relative pronouns (Kim Namkil). Korean especially bears some morphological resemblance to some languages of the Eastern Turkic group, namely Sakha (Yakut).

It is also considered likely that Korean is related in some way to Japanese, since the two languages have a similar grammatical structure. Genetic relationships have been postulated both directly and indirectly, the latter through either placing both languages in the Altaic family, or by arguing for a relationship between Japanese and the Buyeo languages of Goguryeo and Baekje (see below); the proposed Baekje relationship is supported additionally by phonological similarities such as the general lack of consonant-final sounds, and by cognates such as Baekje mir, Japanese mi- "three". Furthermore, there are known cultural links between Baekje and Japan, it even being likely that the Baekje upper classes fled to Japan when the kingdom fell. Others argue, however, that the similarities are not due to any genetic relationship, but rather to a sprachbund effect. See East Asian languages for morphological features shared among languages of the East Asian sprachbund, and Japanese language classification for further details on the possible relationship.

Of the ancient languages attested in the Korean peninsular, modern Korean is believed to be a descendent of the languages of Samhan and Silla; it is unknown whether these are related to the Buyeo languages, though many Korean scholars believe they were mutually intelligible, and the collective basis of what in the Goryeo period would merge to become Middle Korean (the language before the changes that the Seven-Year War brought) and eventually Modern Korean. The Jeju dialect preserves some archaic features that can also be found in Middle Korean, whose arae a is retained in dialect as a distinct vowel.

There are also fringe theories proposing various other relationships; for example, a few linguists such as Homer B. Hulbert have also tried to relate Korean to the Dravidian languages through the similar syntax in both.

Korean has several dialects (called mal [literally speech], bang-eon, or saturi in Korean). The standard language (pyojuneo or pyojunmal) of South Korea is based on the dialect of the area around Seoul, and the standard for North Korea is based on the dialect spoken around P'yŏngyang. These dialects are similar, and are in fact all mutually intelligible, except the dialect of Jeju Island (see Jeju Dialect). The dialect spoken in Jeju is classified as a different language by some Korean linguists. One of the most notable differences between dialects is the use of stress: speakers of Seoul dialect use stress very little, and standard South Korean has a very flat intonation; on the other hand, speakers of Gyeongsang dialect have a very pronounced intonation that, to Western ears, often sounds European.

There is a very close connection between the dialects of Korean and the regions of Korea, since the boundaries of both are largely determined by mountains and seas. Here is a list of traditional dialect names and locations:

The IPA symbol <͈> (a subscript double straight quotation mark) is used to denote the tensed consonants /p͈, t͈, k͈͈, ʨ͈, s͈/. Its official use in the Extended IPA is for 'strong' articulation, but is used in the literature for faucalized voice. The Korean consonants also have elements of stiff voice, but it is not yet known how typical this is of faucalized consonants. They are produced with a partially constricted glottis and additional subglottal pressure in addition to tense vocal tract walls, laryngeal lowering, or other expansion of the larynx.

Sometimes the tense consonants are indicated with the apostrophe-like symbol <ʼ>, but this is inappropriate, as IPA <ʼ> represents the ejective consonants, with their piston-like upward glottal movement and non-pulmonic air pressure, which the Korean tense consonants do not share.

Korean has 8 different vowel qualities and a length distinction. Two more vowels, the close-mid front rounded vowel /ø/ and the close front rounded vowel /y/, can still be heard in the speech of some older speakers, but they have been largely replaced by the diphthongs [we] and [wi] respectively. In a 2003 survey of 350 speakers from Seoul, nearly 90% pronounced the vowel 'ㅟ' as [wi]. Length distinction is almost completely lost; length distinction for all vowels can still be heard from older speakers, but almost all younger speakers either do not distinguish length consistently or do not distinguish it at all. The distinction between /e/ and /ɛ/ is another decreasing element in the speech of some younger speakers, mostly in the area of Seoul, whereas in other dialectal areas the two vowels can be distinctly heard. For those speakers who do not make the difference [e] seems to be the dominant form. Long /ʌː/ is actually [əː] for most speakers.

/s/ becomes an alveolo-palatal[ɕ] before [j] or [i]. This occurs with the tense fricative and all the affricates as well. At the end of a sentence, /s/ is changed to /t/. Example: David (다윗)

/h/ becomes a bilabial[ɸ] before [o] or [u], a palatal[ç] before [j] or [i], a velar[x] before [ɯ], a voiced [ɦ] between voiced sounds, and a [h] elsewhere.

/p, t, ʨ, k/ become voiced [b, d, ʥ, g] between voiced sounds.

/l/ becomes alveolar flap [ɾ] between vowels, [l] or [ɭ] at the end of a syllable or next to another /l/, disappears at the beginning of a word before [j] in normal speech, and otherwise becomes [n] in normal speech.

Korean syllables may not start or end with consonant clusters, except in a few cases. Consequently, consonant clusters in Korean are usually limited to clusters of two consonants where two syllables have been joined.

Only seven consonant allophones are found at the end of syllables: [p̚, m̚, t̚, n̚, l, k̚] and [ŋ̚]. Syllable-final stops are all unreleased.

Traditionally, the Korean language has had strong vowel harmony; that is, in pre-modern Korean, as in most Altaic languages, not only did the inflectional and derivational affixes (such as postpositions) change in accordance to the main root vowel, but native words also adhered to vowel harmony. It is not as prevalent in modern usage, although it remains strong in onomatopoeia, adjectives and adverbs, interjections, and conjugation. There are also other traces of vowel harmony in Korean.

There are three classes of vowels in Korean: positive, negative, and neutral. The vowel ŭ is considered partially a neutral and negative vowel. The vowel classes loosely follow the negative and positive vowels; they also follow orthography. Exchanging positive vowels with negative vowels usually creates different nuances of meaning, with positive vowels sounding diminutive and negative vowels sounding crude.

Some examples:

Onomatopoeia:

퐁당퐁당 (pongdangpongdang) and 풍덩풍덩 (pungdeongpungdeong),light and heavy water splashing

Korean is an agglutinative language. The basic form of a Korean sentence is Subject-Object-Verb (SOV), and modifiers precede the modified word. As a side note, a sentence can break the SOV word order, however, it must end with the verb. The following is an example of contrast between the Korean and English word order. In English, one would say, "I'm going to the store to buy some food." But in Korean the sentence would be: *"I food to-buy in-order-to store-to going-am."

In Korean, "unnecessary" words (see theme and rheme) can be left out of a sentence as long as the context makes the meaning clear. A typical exchange might translate word-for word to the following:

H: "가게에 가세요?" (gage-e gaseyo?)

G: "예." (ye.)

H: *"store-to going?"

G: "yes."

which in English would translate to:

H: "Going to the store?"

G: "Yes."

Unlike most European languages, Korean does not conjugate verbs using agreement with the subject, and nouns have no gender. Instead, verb conjugations depend upon the verb tense and on the relation between the people speaking. When talking to or about friends, you would use one conjugate ending, to your parents, another, and to nobility/honoured persons, another. This loosely echoes the T-V distinction of most Indo-European languages.

The relationship between a speaker or writer and his or her subject and audience is paramount in Korean, and the grammar reflects this. The relationship between speaker/writer and subject is reflected in honorifics, while that between speaker/writer and audience is reflected in speech level.

When talking about someone superior in status, a speaker or writer has to use special nouns or verb endings to indicate the subject's superiority. Generally, someone is superior in status if he/she is an older relative, a stranger of roughly equal or greater age, or an employer, teacher, customer, or the like. Someone is equal or inferior in status if he/she is a younger stranger, student, employee or the like. On rare occasions (like when someone wants to pick a fight), a speaker might speak to a superior or stranger in a way normally only used for, say, animals, but it would be foolhardy to do so without seriously considering the consequences to one's physical safety first.

There are no fewer than 7 verb paradigms or speech levels in Korean, and each level has its own unique set of verb endings which are used to indicate the level of formality of a situation. Unlike "honorifics" — which are used to show respect towards a subject — speech levels are used to show respect towards a speaker's or writer's audience. The names of the 7 levels are derived from the non-honorific imperative form of the verb 하다 (hada, "do") in each level, plus the suffix 체 ('che', Hanja: 體), which means "style."

The highest 5 levels use final verb endings and are generally grouped together as jondaemal (존대말), while the lowest 2 levels (해요체 haeyoche and 해체 haeche) use non-final endings and are called 반말 (banmal, "half-words") in Korean. (The haeyoche in turn is formed by simply adding the non-final ending -요 (-yo) to the haeche form of the verb.)

The core of the Korean vocabulary is made up of native Korean words. More than 50% of the vocabulary (up to 70% by some estimates), however, especially scholarly terminology, are Sino-Korean words, either

Korean has two number systems: one native, and one borrowed from the Chinese.

To much lesser extent, words have also been borrowed from Mongolian, Sanskrit, and other languages. In modern times, some words have also been borrowed from Japanese, Western languages such as German and more recently English. Concerning daily usage vocabulary except what can be written in hanja, more words have possibly been borrowed from English than from any other language.

North Korean vocabulary shows a tendency to prefer native Korean over Sino-Korean or foreign borrowings. By contrast, South Korean may have several Sino-Korean or foreign borrowings which tends to be absent in North Korean.

The Korean language was originally written using "Hanja", or Chinese characters; it is now mainly written in Hangul, the Korean alphabet, optionally mixing in Hanja to write Sino-Korean words. South Korea still teaches 1800 Hanja characters to its children, while the North abolished the use of hanja decades ago.

Hangul consists of 24 letters — 14 consonants and 10 vowels that are written in syllabic blocks of 2 to 5 components. Unlike the Chinese writing system (including JapaneseKanji), Hangul is not an ideographic system.

Below is a chart of the Korean alphabet's symbols and their canonical IPA values:

Modern Korean is written with spaces between words, a feature not found in Chinese and Japanese. Korean punctuation marks are almost identical to Western ones. Traditionally, Korean was written in columns from top to bottom, right to left, but is now usually written in rows from left to right, top to bottom.

In North Korea, palatalization of /si/ is optional, and /ʨ/ can be pronounced as [z] in between vowels.

Words that are written the same way may be pronounced differently, such as the examples below. The pronunciations below are given in Revised Romanization, McCune-Reischauer and Hangul, the last of which represents what the Hangul would be if one writes the word as pronounced.

* Similar pronunciation used in the North whenever the hanja "的" is attached to a Sino-Korean word ending in ㄴ, ㅁ or ㅇ (this rule only applies to one-character Sino-Korean words ending in any consonant or vowel in the South).

When a ㄴ-ㄴ combination is pronounced as ll, the original Hangul spelling is kept in the North, while the Hangul is changed in the South.

규률

규율

rules

gyuyul (kyuyul)

In words where the original hanja is spelt "렬" or "률" and follows a vowel, the initial ㄹ is not pronounced in the North, making the pronunciation identical with that in the South where the ㄹ is dropped in the spelling.

Some words have different spellings and pronunciations in the North and the South, some of which were given in the "Phonology" section above:

Word

Meaning

Remarks

North spelling

North pronun.

South spelling

South pronun.

력량

ryeongryang (ryŏngryang)

역량

yeongnyang (yŏngnyang)

strength

Korean words originally starting in r or n have their r or n dropped in the South Korean version if the sound following it is an i or y sound.

로동

rodong (rodong)

노동

nodong (nodong)

work

Korean words originally starting in r have their r changed to n in the South Korean version if the sound following it is a sound other than i or y.

원쑤

wonssu (wŏnssu)

원수

wonsu (wŏnsu)

enemy

"Enemy" and "military general" are homophones in the South, as they originally were in the North. Possibly to avoid referring to Kim Il-sung / Kim Jong-il as the enemy, the second syllable of "enemy" is now written and pronounced 쑤 in the North.

When transcribing foreign words from languages that do not have contrasts between aspirated and unaspirated stops, North Koreans generally use tensed stops for the unaspirated ones while South Koreans use aspirated stops in both cases.

페

pe (p'e)

폐

pye (p'ye)

lungs

All hanja pronounced as pye (p'ye) in the South are pronounced as pe (p'e) in the North. The spelling is also accordingly different.

In general, when transcribing place names, North Korea tends to use the pronunciation in the original language more than South Korea, which often uses the pronunciation in English. For example: